Photosensitive paste, a plasma display, and a method for the production thereof

ABSTRACT

To provide a photosensitive paste that permits pattern formation with a high aspect ratio and a high accuracy and to provide a plasma display including the photosensitive paste, by using a photosensitive paste that includes, as essential components, an inorganic particles and an organic component that contains a photosensitive compound with the difference between the average refractive index of the organic component and the average refractive index of the inorganic particles being 0.1 or less.

This application is a national stage application of PCT/JP96/01596,filed Jun. 12, 1996.

TECHNICAL FIELD

The present invention relates to a novel photosensitive paste, a plasmadisplay produced thereof, and a production method thereof.

The photosensitive paste of the present invention is used for patternformation for various displays, including plasma display andmatrix-addressed plasma liquid crystal display, and circuit materials.Such a plasma display can be used in large-size TV sets and computerdisplays.

BACKGROUND TECHNOLOGY

In the fields of display and circuit material, demands are recently veryhigh for techniques for highly accurate pattern formation with inorganicmaterials.

As increasingly small, fine-definition products have been developed inthe field of display, demands are very high for advanced techniques foraccurate pattern formation. For the production of a barrier rib thatdivides the pixels on the plasma display panel, for example, it has beenhoped to develop a material that serves for pattern formation with aninorganic material, such as glass, with a high level of accuracy and ahigh aspect ratio.

In the field of circuit material, on the other hand, useful techniqueshave been needed for accurate processing of ceramic substrates on whichIC's are to be mounted. Screen printing and punching are currently usedfor the pattern formation, but more advanced techniques are needed forhighly accurate pattern formation as smaller circuit devices aredeveloped.

Conventionally, pattern formation with inorganic material has beenfrequently performed by screen printing using a paste consisting ofinorganic particles and an organic binder, followed by firing. Screenprinting, however, is disadvantageous in forming accurate patterns.Another disadvantage is that the formation of a pattern with a highaspect ratio requires many processing steps since multiple-layerprinting is necessary.

To solve this problem, U.S. Pat. No. 4,885,963, U.S. Pat. No. 5,209,688,and JP-A-05-342992 have proposed to perform photolithography using aphotosensitive paste. Since the photosensitive paste is low insensitivity and resolution, however, it is impossible to produce ahigh-definition barrier rib with a high aspect ratio, and therefore, along process consisting of several steps (coating, exposure,development, etc.) is required to form a pattern on a barrier rib up toa large thickness of, for example, 80 μm or more.

U.S. Pat. No. 5,209,688 has also proposed a method in which transferpaper is coated with a photosensitive paste, followed by transferringtransfer film onto a glass substrate, and JP-A-03-57138 has proposed amethod in which grooves on a photoresist layer are filled with adielectric paste to form a barrier rib. Also, U.S. Pat. No. 5,116,271has proposed the use of photosensitive organic film to form a barrierrib. These methods, however, have disadvantages arising from the use oftransfer film, photoresist, or organic film which require additionalmanufacturing processes. It should also be noted that a high-definitionbarrier rib with a high aspect ratio has not been obtained with thesemethods.

Furthermore, manufacturing of plasma displays sometimes requires patternformation of the insulator layer or dielectric layer in addition to thebarrier rib, and results in problems similar to those with the barrierrib processing.

SUMMARY OF THE INVENTION

The object of the invention is to provide a photosensitive paste thatpermits pattern formation with high accuracy and a high aspect ratio,which is made possible by controlling the refractive index of theorganic and inorganic components in the photosensitive paste in order toreduce the reflection and scattering at the interface between theorganic and inorganic components. Another object of the invention is toprovide a high-definition plasma display and a method for the productionthereof.

The objects of the invention are achieved by a photosensitive pastecomprising, as essential components, inorganic particles and an organiccomponent that contains a photosensitive compound, wherein the averagerefractive index of the inorganic particles, N1, and the averagerefractive index of the photosensitive organic component, N2, meet thefollowing equation:

−0.1≦N1−N2≦0.2

The objects of the invention are also achieved by a photosensitive pastecomprising, as essential components, inorganic particles and an organiccomponent that contains a photosensitive compound, wherein the averagerefractive index of the inorganic particles is in the range of 1.5-1.7.

Furthermore, the objects of the invention are also achieved by a plasmadisplay and its production method wherein the barrier rib is produced bycoating a glass substrate with the paste, followed by exposure,development, and firing.

BEST MODE FOR CARRYING OUT THE INVENTION

The photosensitive paste of the invention comprises inorganic particlesand an organic component containing a photosensitive compound, and formsan inorganic pattern when sintered after a pattern is formed byphotolithography with the photosensitive organic component.

The content of the inorganic particles in the paste should be in therange of 50-98 wt. %, preferably 50-95 wt. %, more preferably 70-95 wt.%, in order to reduce the shrinkage in the firing process to minimizethe deformation caused by the firing.

The present inventors have carried out detailed studies and found that apattern with a high aspect ratio can be produced easily by reducing thedifference between the average refractive index of the organic componentand the average refractive index of the inorganic particles to 0.1 orless, more preferably 0.07 or less.

Also, a pattern with a high aspect ratio can be produced accurately byallowing the average refractive index of the inorganic particles in thephotosensitive paste, N1, and the average refractive index of thephotosensitive organic component, N2, meet the following equation:

−0.05≦N1−N2≦0.1

more preferably,

−0.01≦N1−N2≦0.07

Also, since the organic component can increase in refractive index whenpolymerized, a pattern with a higher aspect ratio is produced when thefollowing equation is met.

0≦N1−N2≦0.07

A pattern with a higher aspect ratio can be produced when the refractiveindex of the organic component polymerized by light irradiation, N3, andthe refractive index of the inorganic particles, N1, meet the followingequation:

−0.03≦N1−N3≦0.03

Any ordinary inorganic material can be used as the inorganic particles.Preferred ones include glass, ceramics (alumina, cordylite, etc.), andmetals (gold, platinum, silver, copper, nickel, palladium, tungsten,ruthenium oxide, and alloys thereof). Glass and ceramics containing, asan essential component, an oxide of silicon, an oxide of boron, or anoxide of aluminum are particularly preferred. Being insulators, they canbe effectively used for producing patterned insulation materials,including barrier ribs for plasma displays and matrix-addressed plasmaliquid crystal displays.

For the diameter of the inorganic particles, a suitable value isselected by considering the shape of the pattern to be formed. Foreffective pattern formation, however, it is preferable to use inorganicparticles with a 50 wt. % particle diameter of 0.1-10 μm, a 10 wt. %particle diameter of 0.4-2 μm, and a 90 wt. % particle diameter of 4-10μm, and with a specific surface of 0.2-3 m²/g.

The use of spherical inorganic particles permits patterning with a highaspect ratio. Specifically, the sphericity coefficient should preferablybe 80% or more. It is more preferred that the average particle diameter,the specific surface, and the sphericity coefficient be 1.5-4 μm,0.5-1.5 m²/g, and 90% or more, respectively.

The sphericity coefficient is defined as the proportion of thoseparticles which look spherical or ellipsoidal under a microscope. Thatis, they are observed as round or elliptical objects under an opticalmicroscope.

A pattern with a more accurate shape can be obtained by using glassparticles that are produced by crushing glass that is 50% or more intransmittance (3 mm thick) for light with a wavelength of 436 nm.

To produce a space plate for a plasma display or a matrix-addressedplasma liquid crystal display, glass particles with a thermal softeningtemperature (Ts) of 350-600° C. should preferably be used at 60 wt. % ormore because a pattern has to be formed on a glass substrate with a lowthermal softening temperature.

To prevent warping from taking place in the glass substrate duringfiring, the glass particles used should preferably have a linear thermalexpansion coefficient of 50-90×10⁻⁷, more preferably 60-90×10⁻⁷.

Concerning the composition of the glass particles, the content ofsilicon oxide should preferably be in the range of 3-60 wt. %. If it isless than 3 wt. %, the denseness, strength and stability of the glasslayer will deteriorate, and the thermal expansion coefficient will beout of the preferred range, possibly causing poor contact with the glasssubstrate. Furthermore, a content of 60 wt. % or less will lead to a lowthermal softening temperature, permitting sintering onto a glasssubstrate.

When included at up to 5-50 wt. %, boron oxide can act to enhance someelectrical, mechanical and thermal characteristics such as electricinsulation, strength, thermal expansion coefficient, and denseness ofthe insulation layer. The glass will deteriorate in stability if theboron oxide content exceeds 50 wt. %.

A glass paste with thermal properties suitable for pattern formation ona glass substrate can be produced by using glass particles that containat least one of the following: bismuth oxide, lead oxide, lithium oxide,sodium oxide, or potassium oxide, at 5-50 wt. %. If the content exceeds50 wt. %, the thermal resistance of the glass will deteriorate, makingsintering onto the glass substrate difficult. In particular, the use ofglass containing bismuth oxide at 5-50 wt. % is advantageous since thepot life of the paste will become long.

Such a glass containing bismuth oxide should preferably contain up to 50wt. % or more of an oxide mixture with the following composition interms of oxide contents:

bismuth oxide: 5-50 wt. %

silicon oxide: 3-60 wt. %

boron oxide: 5-50 wt. %

Glass material that is usually used as insulation material has arefractive index in the range of 1.5-1.9. If the average refractiveindex of the organic component is largely different from the averagerefractive index of the inorganic particles, strong reflection andscattering will occur at the interface between the inorganic particlesand the photosensitive organic component, leading to failure inproducing a high-definition pattern. Since a typical organic compoundhas a refractive index of 1.45-1.7, the inorganic particles and theorganic component can be matched in terms of refractive index if theinorganic particles have a refractive index of 1.5-1.7. More preferably,the latter should be in the range of 1.55-1.65 to permit an organiccomponent to be selected from a wide choice.

The use of glass particles containing oxides of alkali metals, such aslithium oxide, sodium oxide, and potassium oxide, at 3-20 wt. % in totalnot only facilitates the control of the thermal softening temperatureand thermal expansion coefficient, but also reduces the averagerefractive index of glass, allowing the difference in refractive indexbetween the glass particles and the organic component to be decreasedeasily. To increase the stability of the paste, the content of the oxideof alkali metals should preferably be 20 wt. % or less, more preferably15 wt. % or less.

In particular, of the various alkali metals, the use of lithium oxidecan increase the stability of the paste to a relatively high level, andpotassium oxide, even when added in small amounts, can serve to controlthe refractive index. Thus, among other alkali metals, lithium oxide andpotassium oxide can work very effectively.

As a result, it becomes easy to provide inorganic particles that have athermal softening temperature suitable for sintering onto a glasssubstrate and an average refractive index of 1.5-1.7 which permits adecreased difference in refractive indices of the inorganic particlesand the organic component.

Glass containing lead oxide or bismuth may be preferred because they canincrease the thermal softening temperature and water resistance.However, glass particles containing lead oxide and/or bismuth at 10 wt.% or more may often have a refractive index of more than 1.6. Thus, thecombined use of alkali metal oxides, such as lithium oxide, sodiumoxide, and potassium oxide, with lead oxide and/or bismuth oxide canfacilitate the control of the thermal softening temperature, thermalexpansion coefficient, water resistance, and refractive index.

The hardness and workability of glass particles can be improved byadding aluminum oxide, barium oxide, calcium oxide, magnesium oxide,titanium oxide, zinc oxide, and/or zirconium oxide. In particular,aluminum oxide, barium oxide, and zinc oxide are effective. To maintaina required thermal softening temperature, thermal expansion coefficient,and refractive index, their respective content should preferably be 40wt. % or less, more preferably 30 wt. % or less, with their totalcontent being 50 wt. % or less.

The shrinkage that may occur during firing can be controlled by addingto the paste of the invention glass particles or ceramic particles witha thermal softening temperature of 600-900° C. and an aluminum oxide,barium oxide, calcium oxide, magnesium oxide, titanium oxide, zincoxide, and/or zirconium oxide content of 40 wt. % or less. To ensurehigh-accuracy pattern formation, the difference in refractive indexamong the particles used should preferably be 0.1 or less, morepreferably 0.05 or less.

As for circuit materials, particularly for materials for multiple-layersubstrates, ceramics as well as glass can be used as substrate material.Thus the thermal softening temperature may not necessarily be 600° C. orless, so a high-strength substrate can be produced by using materialwith an aluminum oxide content of 25-75 wt. %.

The Becke method can be used to measure the refractive index ofinorganic particles used for the present invention. To ensure highaccuracy, measurement should be carried out at a wave length equal tothat of the light used for exposure that is performed after the coatingwith the paste. In particular, measurement should preferably beconducted by using light with a wave length in the range of 350-650 nm.It is further preferred that refractive index be measured with i-ray(365 nm) or g-ray (436 nm).

A colored pattern can be obtained after firing by adding various metaloxides. For example, a black pattern can be produced by adding blackmetal oxides to the photosensitive paste up to a content of 1-10 wt. %.

In selecting black metal oxides to be used to produce such a blackpattern, at least one, preferably three or more, of the following groupof oxides should be used: Cr, Fe, Co, Mn, and Cu. In particular, ahighly black pattern can be obtained by adding Fe and Mn, each up to 0.5wt. % or more.

Further, patterns of various other colors other than black can beproduced by employing a paste containing inorganic pigments that cancause coloring in red, blue, green, etc. Such colored patterns can beeffectively used in such products as color filters for plasma display.

Particles used for the invention can be a mixture of several sets ofparticles with different compositions. In particular, the shrinkagecaused during firing can be controlled by using several sets of glassparticles and ceramic particles with different thermal softeningtemperatures.

To ensure high-accuracy pattern formation, however, the difference inrefractive index among the several sets of inorganic particles withdifferent compositions used in this case should preferably be 0.1 orless, more preferably 0.05 or less.

The organic component used in the present invention as stated hereinrefers to the organic component of the paste that contains thephotosensitive organic material (i.e., the remainder that is obtainedafter removing the inorganic components from the paste).

The organic component may contain:

(a) 10-90 wt. % of an oligomer or a polymer having a weight-averagemolecular weight of 500-100,000, which oligomer or polymer has acarboxyl group, an unsaturated double bond or both in its molecularstructure;

(b) 10-80 wt. % of a multifunctional acrylate compound and/ormethacrylate compound; or

(c) at least one moiety selected from the group consisting of benzenering, naphthalene ring and sulfur atom with a total content of 10-60 wt.%.

To ensure a high degree of photosensitivity, the photosensitivecomponent in a photosensitive paste as used in the invention shouldpreferably account for 10 wt. % or more, more preferably 30 wt. % ormore, of the organic component.

The organic component should contain at least one of the followingphotosensitive materials: photosensitive monomers, photosensitiveoligomers, and photosensitive polymers. In addition, it may contain, asnecessary, such additives as binders, photopolymerization initiators,ultraviolet ray absorbents, sensitizers, sensitization assistants,polymerization inhibitors, plasticizers, viscosity improvers, organicsolvents, antioxidants, dispersing agents, organic or inorganicsuspending agents, and leveling agents.

There are photo-insolubilizing type and photo-solubilizing typephotosensitive materials. A photo-insolubilizing type photosensitivematerial may contain:

(A) functional monomers, oligomers, or polymers that have one or moreunsaturated groups in each molecule,

(B) a photosensitive compound such as an aromatic diazo compound, anaromatic azide compound, or an organic halogen compound, or

(C) a so-called diazo resin such as a condensation product of diazotizedamine and formaldehyde.

A photo-solubilizing type photosensitive material may contain:

(D) a complex of an inorganic salt of a diazo compound and a organicacid, a quinonediazo compound, etc., or

(E) a product of a quinonediazo compound bonded with a polymer binder,such as naphthoquinone-1,2-diazide-5-sulfonate of phenol or novolakresin.

Any of the photosensitive components listed above can be used for thepresent invention. In particular, those specified under (A) arepreferred as a component of a photosensitive paste because they can beused conveniently in combination with inorganic particles.

The useful photosensitive monomers include compounds with an unsaturatedcarbon-carbon bond, such as methylacrylate, ethylacrylate,n-propylacrylate, isopropylacrylate, n-butylacrylate, sec-butylacrylate,sec-butylacrylate, iso-butylacrylate, tert-butylacrylate,n-pentylacrylate, allylacrylate, benzilacrylate, butoxyethylacrylate,butoxytriethylene glycolacrylate, cyclohexylacrylate,dicyclopentanylacrylate, dicyclopentenylacrylate, 2-ethylhexylacrylate,glycerolacrylate, glycidylacrylate, heptadecafluorodecylacrylate,2-hydroxyethylacrylate, isobonylacrylate, 2-hydroxypropylacrylate,isothexylacrylate, isooctylacrylate, laurylacrylate,2-methoxyethylacrylate, methoxyethylene glycolacrylate,methoxydiethylene glycolacrylate, octafluoropentylacrylate,phenoxyethylacrylate, stearylacrylate, trifluoroethylacrylate, allylatedcyclohexyldiacrylate, 1,4-butanedioldiacrylate, 1,3-butyleneglycoldiacrylate, ethylene glycoldiacrylate, diethyleneglycoldiacrylate, triethylene glycoldiacrylate, polyethyleneglycoldiacrylate, dipentaerythritol hexaacrylate, dipentaerythritolmonohydroxypentaacrylate, ditrimethylol propanetetraacrylate, glyceroldiacrylate, methoxylated cyclohexyldiacrylate, neopentylglycoldiacrylate, propylene glycoldiacrylate, polypropyleneglycoldiacrylate, triglycerol diacrylate, trimethylolpropanetriacrylate, acryl amide, aminoethylacrylate, phenylacrylate,phenoxyethylacrylate, benzilacrylate, 1-naphthylacrylate,2-naphthylacrylate, bisphenol-A-diacrylate, a diacrylate of an additionproduct of bisphenol-A-ethyleneoxid, a diacrylate of an addition productof bisphenol-A-propyleneoxide, thiophenolacrylate, andbenzilmercaptanacrylate; monomers formed by replacing 1-5 of thehydrogen atoms in the aromatic ring of the above compounds with chlorineor bromine atoms; styrene, p-methylstyrene, o-methylstyrene,m-methylstyrene, chlorinated styrene, brominated styrene,α-methylstyrene, chlorinated α-methylstyrene, brominatedα-methylstyrene, chloromethylstyrene, hydroxymethylstyrene,carboxymethylstyrene, vinylnaphthalene, vinylanthracene, andvinylcarbazole; above-mentioned acrylates with one or all acrylate partsreplaced with methacrylate parts; γ-methacryloxypropyl trimethoxysilane,and 1-vinyl-2-pyrolidone. For the purposes of the present invention,these compounds can be used alone or in combination.

In addition to these, an unsaturated acid such as an unsaturatedcarboxylic acid may be added to improve the developing performance afterlight irradiation. Such unsaturated carboxylic acids include acrylicacid, methacrylic acid, itaconic acid, crotonic acid, maleic acid,fumaric acid, vinylacetic acid, and anhydrides of these acids.

The useful binders include polyvinyl alcohol, polyvinylbutyral,methacrylate polymers, acrylate polymers, acrylate-mathacrylateco-polymers, α-methylstyrene polymers, and butylmathacrylate resins.

Further, oligomers and polymers that are produced by polymerizing atleast one of said compounds having a carbon-carbon bond can also beused.

In polymerizing them, these monomers may be copolymerized with otherphotosensitive monomers in such a way that the content of the former is10 wt. % or more, more preferably 35 wt. % or more.

The developing performance after light irradiation can be improved byusing an unsaturated acid such as an unsaturated carboxylic acid as themonomer for copolymerization. Useful unsaturated carboxylic acidsinclude acrylic acid, methacrylic acid, itaconic acid, crotonic acid,maleic acid, fumaric acid, vinylacetic acid, and anhydrides of theseacids.

The resultant polymers or oligomers having acid groups such as carboxylgroup in their side chains should preferably have an acid value in therange of 50-180, more preferably 70-140. The developable range will benarrow if the acid value is less than 50. If the acid value exceeds 180,on the other hand, the unexposed portions will be small in solubility tothe developing solution, but the use of a developing solution with anincreased concentration will cause the removal of exposed portions,making it difficult to produce high-definition patterns.

Useful photosensitive polymers or photosensitive oligomers can beproduced by adding photosensitive groups to the side chains or themolecular ends of the polymers or oligomers listed above.

Photosensitive groups having an ethylenically unsaturated group arepreferred. Such ethylenically unsaturated groups include vinyl, allyl,acryl, and methacryl.

The addition of such side chains to oligomers or polymers can be carriedout by allowing a glycidyl- or isocyanate-containing ethylenicallyunsaturated compound, acrylic acid chloride, methacrylic acid chlorideor allylchloride to undergo addition reaction with the mercapto group,amino group, hydroxyl group, or carboxyl group in the polymers.

Such ethylenically unsaturated compounds with glycidyl groups includeglycidyl acrylate, glycidyl methacrylate, allylglycidyl ethers, glycidylethylacrylate, crotonic glycidyl ethers, iso crotonic glycidyl ethers.

Useful ethylenically unsaturated compounds with isocyanate groupsinclude (meth)acryloyl isocyanate, and (meth)acryloyl ethylisocyanate.

Such aglycidyl- or isocyanate-containing ethylenically unsaturatedcompound, acrylated chloride, methacrylated chloride, and allyl chlorideshould preferably be added to 0.05-1 equivalent to the mercapto, amino,hydroxy, or carboxy group in the polymer.

Useful photopolymerization initiators include benzophenone, o-methylbenzoylbenzoate, 4,4-bis(dimethylamine)benzophenone,4,4-bis(diethylamino)benzophenone, 4,4-dichlorobenzophenone,4-benzoyl-4-methyldiphenylketone, dibenzilketone, fluorenone,2,2-diethoxyacetophenon, 2,2-dimethoxy-2-phenyl-2-phenylacetophenon,2-hydroxy-2-methylpropiophenon, p-t-butyldichloroacetophenon,thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone,2-isopropylthioxanthone, diethylthioxanthone, benzil, benzildimethylketanol, benzilmethoxyethyl acetal, benzoin, benzoinmethyl ether,benzoinbutyl ether, anthraquinone, 2-t-butylanthraquinone,2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone,dibenzosuberone, methyleneanthrone, 4-azidebenzalacetophenon,2,6-bis(p-azidebenzylidene)cyclohexanone,2,6-bis(p-azidebenzylidene)-4-methylcyclohexanone,2-phenyl-1,2-butadione-2-(o-methoxycarbonyl)oxime,1-phenyl-propanedione-2-(o-ethoxycarbonyl)oxime,1,3-diphenyl-propanetrione-2-(o-ethoxycarbonyl)oxime,1-phenyl-3-ethoxy-propanetrione-2-(o-benzoyl)oxime, Michler's ketone,2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone,naphthalenesulfonylchloride, quinolinesulfonylchloride,N-phenylthioacridone, 4,4-azobisisobutyronitril, diphenyldisulfide,benzthiazoledisulfide, triphenylphosphine, camphorquinone, carbontetrabromide, tribromophenylsulfone, and benzoin peroxide; andcombinations of such photoreducing pigments as eosin and methylene bluewith reducing agents such as ascorbic acid and triethanolamine. For thepurposes of the invention, one or more of these can be used incombination. A photopolymerization initiator should preferably be addedto 0.05-10 wt. %, more preferably 0.1-5 wt. %, of the photosensitivecomponent. Photosensitivity can be insufficient if the amount of thepolymerization initiator added is too small, while the persistence rateof the exposed portions can be too small if the amount of thepolymerization initiator added is too large.

The addition of an ultraviolet ray absorbent can be effective. A highaspect ratio, high definition, and high resolution may be achieved byadding a compound with high ultraviolet ray absorbing performance. Thepreferred ultraviolet ray absorbents include organic dyes and organicpigments, particularly red organic pigments that absorb ultraviolet rayin the wavelength range of 350-450 nm. Specifically, they include azodyes, aminoketone dyes, xanthene dyes, quinoline dyes, aminoketone dyes,anthraquinone dyes, benzophenone dyes, diphenylcyanoacrylate dyes,triazine dyes, and p-aminobenzoic acid dyes. Organic dyes are preferredbecause even when added as light absorbers, they will not remain in thefired insulation film, minimizing the deterioration in the performanceof the insulation film. Of the dyes listed above, azo dyes andbenzophenone dyes are particularly preferred. The content of such anorganic dye should preferably be 0.05-5 parts by weight. The effect ofthe ultraviolet ray absorbent will not be sufficient if the content isless than 0.05 wt. %, while the performance of the fired insulation filmwill not be sufficient if the content is above 5 wt. %. It is morepreferred that the content be in the range of 0.05-1 wt. %. A typicalprocess of adding an ultraviolet ray absorbent comprising an organic dyeis as follows: the organic dye is dissolved in an organic solvent toform a solution, followed either by kneading it into a paste, or byadding inorganic particles to the organic solvent and drying it. By thelatter method, so-called encapsulated particles in which the surface ofeach organic particle is coated with the organic compound are produced.

In some embodiments of the invention, such metals as Pb, Fe, Cd, Mn, Co,and Mg or their oxides contained in the inorganic particles may reactwith the photosensitive component of the paste to cause quick gelationof the paste, making it impossible to use it for coating. To preventsuch a reaction, it is preferred that a stabilizing agent be added toinhibit the gelation. Preferred stabilizing agents include triazolecompounds. In particular, preferred triazole compounds includebenzotriazole derivatives, of which benzotriazole can work effectively.A typical surface treatment of glass particles with benzotriazole asperformed for the invention is as follows: a required amountbenzotriazole relative to the amount of inorganic particles is dissolvedin an organic solvent such as methyl acetate, ethyl acetate, ethylalcohol, or methyl alcohol, and the particles are immersed in thesolution for 1-24 hours to ensure adequate immersion, followed by airdrying preferably at a temperature of 20-30° C. to evaporate thesolvent, thus producing triazole-treated particles. The amount of thestabilizing agent used (stabilizing agent/inorganic particles) shouldpreferably be 0.05-5 wt. %.

A sensitizer is added to improve the sensitivity. Specifically, suchsensitizers include 2,4-diethylthioxanthone, isopropylthioxanthone,2,3-bis(4-diethylaminobenzal)cyclopentanone,2,6-bis(4-dimethylaminobenzal)cyclohexanone,2,6-bis(4-dimethylaminobenzal)-4-methylcyclohexanone, Michler's ketone,4,4-bis(diethylamino)-benzophenone, 4,4-bis(dimethylamino)chalcone,4,4-bis(diethylamino)chalcone, p-dimethylaminocinnamylideneindanone,p-dimethylaminobenzylideneindanone,2-(p-dimethylaminophenylvinylene)-isonaphthothiazole,1,3-bis(4-dimethylaminobenzal)acetone,1,3-carbonyl-bis(4-diethylaminobenzal)acetone,3,3-carbonyl-bis(7-diethylaminocoumalin), N-phenyl-N-ethylethanolamine,N-phenylethanolamine, N-tolyldiethanolamine, N-phenylethanolamine,dimethylaminoisoamyl benzoate, diethylaminoisoamyl benzoate,3-phenyl-5-benzoylthiotetrazole, and1-phenyl-5-ethoxycarbonylthiotetrazole. One or more of these can be usedfor the purposes of the invention. Some sensitizers can also work asphoptopolymerization initiators. When a sensitizer is added to aphotosensitive paste as used for the invention, its content shouldpreferably be 0.05-10 wt. %, more preferably 0.1-10 wt. %, relative tothe photosensitive component. The sensitivity to light may not beimproved significantly if the amount of the sensitizer is too small,while the persistence rate of the exposed portions can be too small ifthe amount of the sensitizer is too large.

A polymerization inhibitor is added to improve the thermal stabilityduring storage. Specifically, such polymerization inhibitors includehydroquinone, monoesterified compounds of hydroquinone,N-nitrosodiphenylamine, phenothiazine, p-t-butylcatechol,N-phenylnaphthylamine, 2,6-di-t-butyl-p-methylphenol, chloranil, andpyrogallol. When a polymerization inhibitor is added, its content shouldpreferably be 0.001-1 wt. % of the photosensitive paste.

Useful plasticizers include dibutylphthalate, dioctylphthalate,polyethylene glycol, and glycerin.

An antioxidant is added to prevent the oxidation of an acrylateco-polymer during storage. Specifically, such antioxidants include2,6-di-t-butyl-p-cresol, butylated hydroxyanisole,2,6-di-t-4-ethylphenol, 2,2-methylene-bis-(4-methyl-6-t-butylphenol),2,2-methylene-bis-(4-ethyl-6-t-butylphenol),4,4-bis-(3-methyl-6-t-butylphenol),1,1,3-tris-(2-methyl-6-t-butylphenol),1,1,3-tris-(2-methyl-4-hydroxy-t-butylphenyl)butane, bis[3,3-bis-(4-hydroxy-3-t-butylphenyl)butyric acid] glycol esters,dilaurylthiodipropionate, and triphenylphosphite. When an antioxidant isadded, its content should preferably be 0.001-1 wt. % of the paste.

When the viscosity of the solution is to be controlled, an organicsolvent may be added to the photosensitive paste of the invention. Theuseful organic solvents for this include methylcellosolve,ethylcellosolve, butylcellosolve, methylethylketone, dioxane, acetone,cyclohexanone, cyclopentanone, isobutyl alcohol, isopropyl alcohol,tetrahydrofuran, dimethylsulfoxide, γ-butyrolactone, bromobenzene,chlorobenzene, dibromobenzene, dichlorobenzene, bromobenzoate,chlorobenzoate, and mixtures of organic solvents containing one or moreof them.

The refractive index of the organic component is defined as therefractive index of that organic component in the paste at the time ofexposure of the photosensitive component to light. When exposure is tobe performed after the paste-coating and drying processes, therefractive index is defined as the refractive index of the organiccompound in the paste after the drying process. In a typical method, theglass substrate is coated with a paste and then dried at 50-100° C. for1-30 min, followed by the measurement of the refractive index.

For the purposes of the present invention, common refractive indexmeasurement methods such as the ellipsometric method or the V blockmethod are preferred, and the measurement should be performed at thesame wavelength as that of the light used for the exposure. Inparticular, measurement should preferably be carried out using lightwith a wavelength in the range of 350-650 nm. Further, measurement ofthe refractive index should preferably be performed by using i-ray (365nm) or g-ray (436 nm).

The refractive index of the organic component polymerized by lightirradiation can be measured by irradiating only the organic componentwith the same light as that used for the light irradiation of the paste.

Glass particles containing 10 wt. % or more bismuth oxide or lead oxidethat can be fired onto a glass substrate can have a refractive index of1.6 or more, and in such a case, the organic compound should have a highrefractive index.

In such a case, a substance with a high refractive index should be addedto the organic component. To increase the refractive index, the additionof a compound that contains sulfur atoms, bromine atoms, iodine atoms,naphthalene rings, biphenyl rings, anthracene rings, or carbazole ringsat 10 wt. % or more to the organic component is effective. Therefractive index can also be increased by adding benzene rings at up to20 wt. %.

In particular, the refractive index of the organic component can beeasily increased by adding more than 10 wt. % of sulfur atoms ornaphthalene rings. If the content is 60 wt. % or more, however, thesensitivity to light may decrease undesirably, so the total content ofthe sulfur atoms and naphthalene rings should preferably be in the rangeof 10-60 wt. %.

An effective method for introducing sulfur atoms, bromine atoms, andnaphthalene rings into the organic component is the use of a compoundconsisting of photosensitive monomers or binders that contain sulfuratoms or naphthalene rings. Typical polymers produced from monomerscontaining sulfur atoms in their molecular structure include thoseexpressed by formulae (a), (b) and (c) below, where R in the structuralformulae denotes a hydrogen atom or a methyl group.

A sensitizer to be used should absorb light of the exposure wavelength.With such a sensitizer, the refractive index extremely increases in thevicinity of the wavelength where absorption occurs, so the refractiveindex of the organic component can be increased by adding a sensitizerin large amounts. In such a case, the sensitizer can be added at 0.5-10wt. %, more preferably 1-6 wt. %, of the paste.

To produce a paste, the required components such as inorganic particles,ultraviolet ray absorbent, photosensitive polymer, photosensitivemonomer, photopolymerization initiator, glass frit, and solvent areprepared to provide a mixture of a required composition, followed byprocessing by means of a three-roll mill or a kneading machine to ensurehomogeneous mixing and dispersion.

The viscosity of the paste is adjusted, as required, by controlling theamounts of the inorganic particles, viscosity improver, organic solvent,plasticizer, and suspending agent to be added. Its range should be2,000-200,000 cps (centipoise). When the spin coating method is used tocoat glass substrates, the viscosity should preferably be 200-5,000 cps.It should preferably be 50,000-200,000 cps when the screen printingmethod is used to apply a single coat with a thickness of 10-20 μm,while it should preferably be 1,000-20,000 cps when a blade coater or adye coater is used.

Some examples of using photosensitive pastes for pattern formation aredescribed below, but they should place no limitations on the invention.

A photosensitive paste is applied over the entire surface or a part of aglass substrate, a ceramic substrate, or a polymer film. A common methodsuch as screen printing, bar coater, roll coater, dye coater, or bladecoater can be used for the coating. The coat thickness can be adjustedby using an appropriate number of coats, coater gap, screen mesh, andpast viscosity.

When a paste is applied over a substrate, the surface of the substratemay be treated to achieve a close contact between the substrate andcoat. Useful agents for such surface treatment include silane couplingagents, such as vinyl trichlorosilane, vinyl trimethoxy silane, vinyltriethoxy silane, tris-(2-methoxyethoxy)vinyl silane, γ-glycidoxypropyltrimethoxy silane, γ-(methacryloxypropyl)trimethoxy silane,γ(2-aminoethyl)aminopropyl trimethoxy silane, γ-chloropropyl trimethoxysilane, γ-mercaptopropyl trimethoxy silane, and γ-aminopropyl triethoxysilane; and organic metal compounds such as organic titanium compounds,organic aluminum compounds, and organic zirconium compounds. Such silanecoupling agents or organic metal compounds are used as a 0.1-5% solutionin such an organic solvent as ethylene glycol monomethyl ether, ethyleneglycol monoethyl ether, methyl alcohol, ethyl alcohol, propyl alcohol,and butyl alcohol. Then, the surface treatment liquid is applieduniformly over a substrate by means of a spinner etc., followed bydrying at 80-140° C. for 10-60 min to achieve surface treatment.

When a paste is applied to a film, the exposure may be performed eitherafter drying the paste on the film, or after adhering the film on aglass or ceramic substrate.

A photosensitive green sheet for circuit materials or displays can beproduced by applying the photosensitive paste of the invention over suchmaterials as polyester film. A photosensitive paste layer with a uniformthickness can be produced by transferring this green sheet onto a glasssubstrate.

After the coating, light exposing equipment is used to perform exposure.Exposure is generally carried out with the masked exposure method usinga photomask, as in ordinary photolithography. The mask used may be of anegative type or a positive type depending on the photosensitive organiccomponent.

Direct pattern formation by means of a red or blue visible laser beam orAr ion laser beam may be performed instead of using a photomask.

Exposure devices such as stepper exposer or proximity exposer may beused. For light exposure of a large area, a photosensitive paste may beapplied over a glass or other substrate, followed by performing exposurewhile conveying the substrate to allow a large area to be exposed bymeans of a light exposer with a small light source.

The active light sources that can be used effectively include visiblelight, near ultraviolet light, ultraviolet light, electron beam, X-ray,and laser beam. Of these, ultraviolet light is preferred, and suchsources as low-pressure mercury lamp, high-pressure mercury lamp,extra-high pressure mercury lamp, halogen lamp, and germicidal lamp canbe used. Of these, the extra-high pressure mercury lamp is preferred.The optimum exposure conditions depend on the coat thickness, but anextra-high pressure mercury lamp with an output of 1-100 mW/cm² shouldpreferably be used for exposure for 0.5-30 min.

Oxygen barrier film may be provided over the applied photosensitivepaste to improve the shape of the pattern. Useful materials for suchoxygen barriers include PVA membrane, cellulose membrane, and polyesterfilm.

PVA membrane may be produced by coating a substrate uniformly with0.5-5.0 wt. % aqueous solution using a spinner etc., followed by dryingat 70-90° C. for 10-60 min to evaporate water. It is preferred that asmall amount of alcohol be added to the aqueous solution to improve thewettability with the insulation film, thus facilitating the evaporation.The PVA solution should more preferably be in the concentration range of1-3 wt. %. A concentration in this range will further improve thesensitivity. It is thought that the PVA coating can improve thesensitivity because of the following mechanism: oxygen in the atmosphereis believed to reduce the sensitivity for photo-curing, but the PVAmembrane can block undesirable oxygen to improve the sensitivity tolight exposure.

When transparent films such as polyester, polypropylene, or polyethyleneare used, such film may be adhered over the applied photosensitivepaste.

After the light exposure, development is carried out by making use ofthe difference in solubility to developing solution between the exposedand unexposed portions. Such a method as dipping, spraying, or brushingmay be used for this purpose.

An organic solvent that can dissolve the organic component in thephotosensitive paste can be used for the development solution. Water maybe added to the organic solvent as long as its dissolving power is notreduced significantly. Alkaline aqueous solution may be used when thephotosensitive paste contains a compound with an acid group such ascarboxyl. Although the alkaline aqueous solution can be a metallicalkaline solution such as sodium hydroxide solution, sodium carbonatesolution, or calcium hydroxide solution, the use of an organic alkalinesolution is preferred because the alkaline components can be removedeasily at the time of firing.

Common amine compounds can be used as such organic alkaline compounds.Specifically, they include tetramethylammonium hydroxide,trimethylbenzylammonium hydroxide, monoethanol amine, and diethanolamine. The concentration of said alkaline solution should generally be0.01-10 wt. %, more preferably 0.1-5 wt. %. The soluble portions willnot be removed if the alkali concentration is too low, while anexcessively high alkali concentration will cause peeling of patternedportions and corrosion of soluble portions.

At the time of development, the developing temperature should preferablybe 20-50° C. to facilitate process control.

Firing is then performed in a kiln. The atmosphere and temperature usedfor the firing depend on the paste and substrate. Firing is generallyperformed in an atmosphere such as air, nitrogen, or hydrogen. The kilnto be used may be a batch-type kiln or a belt-type continuous kiln.

The firing temperature should be 400-1,000° C. When pattern formation isperformed on a glass substrate, it should be maintained at 520-610° C.for 10-60 min to ensure firing.

Each of the processes for coating, light exposure, development, andfiring may include a heating step at 50-300° C. for such purposes asdrying and preliminary reaction.

A glass substrate with a space plate as produced by the above processesmay be used at the front or rear of a plasma display. It may also beused as the substrate provided for electric discharge from the addressedportions in a matrix-addressed plasma liquid crystal display.

Phosphor is applied between the barrier ribs produced above, followed bysandwiching them between a front and a rear glass substrate, and sealingthem up with such a rare gas as helium, neon, or xenon, to produce apanel for plasma display.

Then, driver ICs are installed to complete the plasma display.

The size of each pixel has to be reduced to enhance the definition ofthe plasma display, i.e., to increase the number of pixels in a displayof the same size. The pitch of the barrier rib has to be reduced toachieve this, but a decreased pitch will cause a decrease in thedischarge space and a decrease in the phosphor-coated area, resulting ina reduced brightness. Specifically, a 42-in. high-resolution display forTV (1920×1035 pixels) or a 23-in. display for office-automationequipment (XGA: 1024×768 pixels) will require a 450×450 μm pixel sizeand a 150 μm pitch for the barrier rib to divide pixels of each color.In this case, a large line width in the barrier rib will make itimpossible to maintain a sufficient discharge space and decrease thephosphor-coated area, thus making it difficult to improve thebrightness.

The present inventors have found that the technology given in thepresent invention serves to reduce the line width in the barrier rib.

In particular, the technology serves to produce a plasma displaycomprising a stripe-type barrier rib with a spacer width of 20-40 μm.Thus the technology is effective for improving the brightness.

Further, by producing a high-definition barrier rib with a height of100-170 μm and a pitch of 100-160 μm, a high-definition plasma displayuseful for high-resolution TVs and computer displays can be provided.

Examples are given below to illustrate the invention more concretely.The examples, however, are not intended to place any limitations on theinvention. The concentrations (%) in examples and comparative examplesare in percentage by weight unless otherwise specified.

A photosensitive paste containing inorganic particles and an organiccomponent is produced in each example. Its production process is asfollows: the materials of the organic component are heated at 80° C.with γ-butyrolactone to ensure dissolution, followed by adding inorganicparticles and kneading them in a kneading machine to produce a paste.Its viscosity was adjusted by controlling the amount of the solventadded. The solvent (γ-butyrolactone) was added to 10-40% of the paste.

Subsequently, several coats were applied by screen printing on a 30×30cm soda-lime glass or quartz glass substrate at a thickness of 100 μm,150 μm, or 200 μm, followed by drying at 80° C. for 30 min.

Then, the substrates were exposed to light through either of the twophoto-masks listed below.

(1) Chromium negative mask with a pitch of 220 μm and a line width of 50μm

(2) Chromium negative mask with a pitch of 150 μm and a line width of 20μm

Light exposure was performed with 2-10 J/cm² of ultraviolet ray from aextra-high pressure mercury lamp with an output of 50 mW/cm².

Subsequently, the substrate was immersed in a 0.5% solution ofmonoethanol amine for development.

The resultant glass substrate was then dried at 80° C. for one hour, andfired at a maximum temperature of 560° C. or 850° C. (maximumtemperature maintained for 30 min).

The resultant substrate was cut into specimens and their cross-sectionswere observed under a scanning electron microscope to determine whethera good pattern had been produced on the barrier rib. Results are shownin Table 3, where “◯” indicates that a good pattern was produced and “×”indicates that a good barrier rib was not obtained due tomissing/destroyed portions in the pattern or due to insufficientdevelopment that left unexposed portions unremoved.

The refractive index of the organic component was adjusted only bycontrolling the organic component in the paste, and it was measuredafter coating and drying with the ellipsometric method using light witha wavelength of 436 nm at 25° C.

EXAMPLE 1

A paste was prepared from 75 g of powdered glass A1 and 25 g of organiccomponent B3 given in Table 1, using 10 g of solvent.

A pattern was formed and firing was performed at 560° C. for 30 min.Results are shown in Table 3.

Using a photosensitive silver paste, stripe-like 3,072 silver wiringlines with a line width of 40 μm, a pitch of 150 μm, and thickness of 10μm were produced over a 360×500 mm soda-lime glass substrate (2.8 mmthick). The paste produced above was then applied over the entire areaup to a thickness of 200 μm, and exposed to light through a photo-maskwith a pitch of 150 μm, line width of 20 μm, total number of 3,080lines, and line length of 350 mm, followed by development and firing toprovide a barrier rib. Subsequently, RGB phosphor pastes were spread byscreen printing, followed by firing at 450° C. for 20 min to provide arear panel for 23-in. plasma display. A 23-in. XGA (1024×768 pixels) canbe produced by bonding this rear panel to a front panel and sealing themup with a gas filled between them.

EXAMPLE 2

A paste was prepared from 75 g of powdered glass A2 and 25 g of organiccomponent B3 given in Table 1, using 15 g of solvent.

A pattern was formed and firing was performed at 560° C. for 10 min.Results are shown in Table 3.

EXAMPLE 3

A paste was prepared from 70 g of powdered glass A3 and 30 g of organiccomponent B4 given in Table 1, using 15 g of solvent.

A pattern was formed and firing was performed at 560° C. for 10 min.Results are shown in Table 3.

EXAMPLE 4

A paste was prepared from 80 g of powdered glass A4 and 20 g of organiccomponent B4 given in Table 1, using 7 g of solvent.

A pattern was formed and firing was performed at 580° C. for 15 min.Results are shown in Table 3.

EXAMPLE 5

A paste was prepared from 80 g of powdered glass A4 and 20 g of organiccomponent B2 given in Table 1, using 11 g of solvent.

A pattern was formed and firing was performed at 580° C. for 15 min.Results are shown in Table 3.

EXAMPLE 6

A paste was prepared from 75 g of powdered glass A5 and 25 g of organiccomponent B1 given in Table 1, using 12 g of solvent.

A pattern was formed and firing was performed at 580° C. for 15 min.Results are shown in Table 3.

EXAMPLE 7

A paste was prepared from 75 g of powdered glass A6 and 25 g of organiccomponent B3 given in Table 1, using 10 g of solvent.

A pattern was formed and firing was performed at 850° C. for 15 min.Results are shown in Table 3.

EXAMPLE 8

A paste was prepared by mixing 60 g of powdered glass A1 and 15 g ofpowdered glass A6 and using 25 g of organic component B3 given in Table1, using 10 g of solvent.

A pattern was formed and firing was performed at 580° C. 30 min. Resultsare shown in Table 3.

COMPARATIVE EXAMPLE 1

A paste was prepared from 75 g of powdered glass A3 and 25 g of organiccomponent B2 given in Table 1, using 10 g of solvent.

A pattern was formed and firing was performed at 560° C. for 10 min.Results are shown in Table 3.

COMPARATIVE EXAMPLE 2

A paste was prepared from 75 g of powdered glass A4 and 25 g of organiccomponent B4 given in Table 1, using 10 g of solvent.

A pattern was formed and firing was performed at 580° C. for 15 min.Results are shown in Table 3.

TABLE 1 Compositions of glass particles used Component A1 A2 A3 A4 A5 A6Li₂O 9 13 2 0 3 3 K₂O 0 0 11 0 0 0 SiO₂ 22 47 47 13 7 38 B₂O₃ 33 21 2118 44 10 Bi₂O₃ 0 0 0 26 26 0 BaO 4 5 5 14 17 5 Al₂O₃ 23 8 8 4 3 35 ZnO 26 6 21 0 5 MgO 7 0 0 0 0 0 CaO 0 0 0 0 0 4 Glass transition 484 469 473486 492 656 temperature Tg (° C.) Thermal softening 524 511 520 538 533800 temperature Ts (° C.) Sphericity coefficient (%) 93 98 94 92 90 90D50 average particle  3.5  3.6  4.0  3.5  4.9  4.9 diameter (μm) Linearthermal expansion 78 82 80 75 75 43 coefficient × 10⁷ (0-400° C.)Refractive index (ng) 1.58 1.58 1.53 1.73 1.68 1.58

TABLE 2 Compositions of organic components used Component B1 B2 B3 B4Photosensitive BMEXS-MA 48% MPS-MA 40% TMPTA 28% TMPTA 28% monomerPhotosensitive polymer 2 24% polymer 2 32% polymer 1 44% polymer 2 44%polymer Photopolymerization MTPMP 10% MTPMP 10% MTPMP 10% MTPMP 10%initiator EPA  6% EPA  6% EPA  6% EPA  6% Ultraviolet ray Sudan  2%Sudan  2% Sudan  2% Sudan  2% absorbent Sensitizer DET 10% DET 10% DET10% DET 10% Refractive index 1.64 1.65 1.56 1.52 (ng)* *: Refractiveindex of organic component applied over glass substrate and dried at 80°C. for 40 min.

TABLE 3 Results of barrier rib formation Pitch/ line width 220 μm · 40μm 50 μm · 30 μm Coat thickness 100 μm 150 μm 200 μm 100 μm 150 μm 200μm Example 1 ◯ ◯ ◯ ◯ ◯ ◯ Example 2 ◯ ◯ ◯ ◯ ◯ X Example 3 ◯ ◯ X ◯ ◯ XExample 4 ◯ ◯ X ◯ ◯ X Example 5 ◯ ◯ ◯ ◯ ◯ X Example 6 ◯ ◯ ◯ ◯ ◯ ◯Example 7 ◯ ◯ ◯ ◯ ◯ ◯ Comparative X X X X X X example 1 Comparative X XX X X X example 2

The abbreviations used in the tables are as follows (the numbers givenIn the formula of Polymers 1-3 shows the molar ratio of each monomer):

TMPTA: trimethylolpropane tryacrylate

TBPMA: tribromophenyl methacrylate

TBB-ADA: tetrabromo-bis-phenol-A diacrylate

BMEXS-MA:

MPS-MA:

PVA: polyvinyl alcohol

Sudan: red azo dye (C₂₄H₂₀N₄O)

Yupinal D50: benzophenone dye (Yupinal D50) C₁₃H₁₀O₅

MTPMP: 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1

EPA: p-ethyl dimethylaminobenzoate

DET: 2,4-diethylthioxanthone

γ-BL: γ-butyrolactone

Polymer-1:

(average molecular weight: 43,000, acid number: 90)

Polymer-2:

(average molecular weight: 32,000, acid number: 95)

Polymer-3:

(average molecular weight: 30,000, acid number: 101)

INDUSTRIAL APPLICABILITY

The photosensitive paste of the present invention makes it possible toperform pattern formation with a high aspect ratio and high accuracy.The invention also makes it possible to carry out large-thickness,high-accuracy pattern formation for displays and circuit materials, aswell as to enhance the definition and simplify the manufacturingprocesses. In particular, high-definition plasma display panels can beproduced easily.

We claim:
 1. A photosensitive paste comprising inorganic particlescomprising glass particles and an organic component comprising aphotosensitive compound, wherein an average refractive index of theinorganic particles, N1, and an average refractive index of the organiccomponent, N2, satisfy the following equation: −0.1≦N2−N1≦0.2, whereinthe inorganic particles contain the glass particles at 60 wt.% or more,and wherein the glass particles contain at least one oxide of bismuth orlead and the total content of said at least one oxide is 5-50 wt.%.
 2. Aphotosensitive paste according to claim 1, wherein the averagerefractive index of the inorganic particles satisfy the followingequation: −0.05≦N2−N1≦0.1.
 3. A photosensitive paste comprisinginorganic particles comprising glass particles and an organic componentcomprising a photosensitive compound, wherein an average refractiveindex of the inorganic particles, N1, and an average refractive index ofthe organic component, N2, satisfy the following equation:−0.1≦N2−N1≦0.2, wherein the inorganic particles contain the glassparticles at 60 wt.% or more, and wherein the glass particles contain atleast one oxide of bismuth or lead with a total content of said at leastone oxide of 5-30 wt.% and wherein the particles also contain at leastone additional oxide of lithium, sodium or potassium with a totalcontent of said at least one additional oxide of 3-15 wt.%.
 4. Aphotosensitive paste comprising inorganic particles comprising glassparticles and an organic component comprising a photosensitive compound,wherein an average refractive index of the inorganic particles, N1, andan average refractive index of the organic component, N2, satisfy thefollowing equation: −0.1≦N2−N1≦0.2, wherein the inorganic particlescontain the glass particles at 60 wt.% or more, and wherein the organiccomponent contains 10-90 wt.% of an oligomer or a polymer having aweight-average molecular weight of 500-100,000, which oligomer orpolymer has a carboxyl group in the molecular structure.
 5. A plasmadisplay panel production method wherein barrier ribs are produced by:(1) coating a glass substrate with a photosensitive paste and (2)exposing said paste to light, said paste comprising inorganic particlesand an organic component comprising a photosensitive compound, whereinan average refractive index of the inorganic particles, N1, and anaverage refractive index of the organic component, N2, satisfy thefollowing equation: −0.1≦N2−N1≦0.2.
 6. The plasma display panelproduction method according to claim 5, wherein the light exposureprocess is performed in one step.
 7. A plasma display panel productionmethod according to claim 5, further comprising developing and firingthe paste.
 8. A plasma display panel production method of claim 5,wherein an average refractive index of the inorganic particles, N1, andan average refractive index of the organic component, N2, satisfy thefollowing equation: −0.05≦N2−N1≦0.1.
 9. A plasma display panelproduction method of claims 5 or 8, wherein the average refractive indexof the inorganic particles is in the range of 1.5-1.7.
 10. A plasmadisplay panel production method of claims 5 or 8, wherein the inorganicparticles contain 60 wt.% or more of glass particles.
 11. A plasmadisplay panel production method of claim 10, wherein the glass particlescontain at least one oxide of lithium, sodium or potassium and the totalcontent of said at least one oxide is 3-20 wt.%.
 12. A plasma displaypanel production method of claim 10, wherein the glass particles contain3-20 wt.% of lithium oxide.
 13. A plasma display panel production methodof claim 10, wherein the glass particles contain 3-60 wt.% of siliconoxide and 5-50 wt.% of boron oxide.
 14. A plasma display panelproduction method of claim 5 or 8, comprising 50-98 parts by weight ofinorganic particles and 5-50 parts by weight of the organic component.15. A plasma display panel production method according of claims 5 or 8,wherein the average refractive index of the inorganic particles is inthe range of 1.55-1.65.
 16. A plasma display panel production method ofclaim 5 or 8, wherein the inorganic particles comprise glass particlescontaining at least one oxide of bismuth or lead and the total contentof said at least one oxide is 5-50 wt.%.
 17. A plasma display panelproduction method of claim 5, wherein the organic component contains0.05-5 wt.% of a compound that can absorb ultraviolet rays.
 18. A plasmadisplay panel production method wherein barrier ribs are produced by:(1) coating a glass substrate with a photosensitive paste and (2)exposing said paste to light, said paste comprising inorganic particlesand an organic component comprising a photosensitive compound, whereinan average refractive index of the inorganic particles is in the rangeof 1.5-1.7.
 19. The plasma display panel production method according toclaim 18, wherein the light exposure process is performed in one step.20. A plasma display panel production method according to claim 18,further comprising developing and firing the paste.
 21. A plasma displaypanel production method of claim 18, wherein an average refractive indexof the inorganic particles, N1, and an average refractive index of theorganic component, N2, satisfy the following equation: −0.05≦N2−N1≦0.1.22. A plasma display panel production method of claim 18, wherein theaverage refractive index of the inorganic particles is in the range of1.55-1.65.
 23. A plasma display panel production method of claims 18 or22, wherein the inorganic particles contain 60 wt.% or more of glassparticles.
 24. A plasma display panel production method of claim 23,wherein the glass particles contain at least one oxide of lithium,sodium or potassium and the total content of said at least one oxide is3-20 wt.%.
 25. A plasma display panel production method of claim 23,wherein the glass particles contain 3-20 wt.% of lithium oxide.
 26. Aplasma display panel production method of claim 23, wherein the glassparticles contain 3-60 wt.% of silicone oxide and 5-50 wt.% of boronoxide.
 27. A plasma display panel production method of claims 18 or 22,comprising 50-98 parts by weight of inorganic particles and 5-50 partsby weight of the organic component.
 28. A plasma display panelproduction method of claim 18, wherein the organic component contains0.05-5 wt.% of a compound that can absorb ultraviolet rays.
 29. Aphotosensitive paste comprising inorganic particles comprising glassparticles and an organic component comprising a photosensitive compound,wherein an average refractive index of the inorganic particles is in therange of 1.5-1.7, wherein the inorganic particles contain the glassparticles at 60 wt.% or more, and wherein the glass particles contain atleast one oxide of bismuth or lead and the total content of said atleast one oxide is 5-50 wt.%.
 30. A photosensitive paste according toclaim 29, wherein the average refractive index of the inorganicparticles is in the range of 1.55-1.65.
 31. A photosensitive pastecomprising inorganic particles comprising glass particles and an organiccomponent comprising a photosensitive compound, wherein an averagerefractive index of the inorganic particles is in the range of 1.5-1.7,wherein the inorganic particles contain the glass particles at 60 wt.%or more, and wherein the glass particles contain at least one oxide ofbismuth or lead with a total content of said at least one oxide of 5-30wt.% and wherein the particles also contain at least one additionaloxide of lithium, sodium or potassium with a total content of said atleast one additional oxide of 3-15 wt.%.
 32. A photosensitive pastecomprising inorganic particles comprising glass particles and an organiccomponent comprising a photosensitive compound, wherein an averagerefractive index of the inorganic particles is in the range of 1.5-1.7,wherein the inorganic particles contain the glass particles at 60 wt.%or more, and wherein the organic component contains 10-90 wt.% of anoligomer or a polymer having a weight-average molecular weight of500-100,000, which oligomer or polymer has a carboxyl group in themolecular structure.